|
Rogue planet redirects here. For other uses, see Rogue Planet.An interstellar planet is a planet that is not gravitationally bound to any star, and that therefore moves through space as an independent object. Several astronomers claim to have detected such objects, but those detections remain unconfirmed. The IAU has declared that by definition, a planet must orbit a star. If that declaration is accepted, then the term "interstellar planet" is an oxymoron. However, this article will use that term since no convenient alternate term has yet found wide acceptance. Interstellar planets may form on their own through gas cloud collapse like stars; or they may originate as ordinary planets ejected from the planetary system that they formed in.
Atmosphere hypothesis In 1998, David J. Stevenson authored a paper entitled "Possibility of Life Sustaining Planets in Interstellar Space." In this paper, Stevenson theorizes that some wandering planets which drift in the vast expanses of cold interstellar space could possibly sustain a thick atmosphere which would not freeze out due to radiative heat loss. The mechanism he proposes which preserves atmosphere formation in these bodies is due to the pressure-induced far infrared radiation opacity of a thick hydrogen-containing atmosphere. It is thought that during planetary system formation, several small protoplanetary bodies may be ejected from the forming system. With the reduced ultraviolet light associated with its increasing distance from the parent star, the planet's predominantly hydrogen and helium containing atmosphere would be easily confined even by an Earth-sized body's gravity. It is calculated that for an Earth-sized planet at a kilobar hydrogen atmospheric pressures in which a convective gas adiabat has formed, geothermal energy from residual core radioisotope decay will be sufficient to heat the surface to temperatures above the melting point of water. Thus, it is proposed that interstellar planetary bodies with extensive liquid water oceans may exist. It is further suggested that the bodies are likely to remain geologically active for long periods of time, providing a geodynamo-created protective magnetosphere and possible sea floor volcanism which could provide an energy source for life. The author admits these bodies will be difficult to detect due to the intrinsically weak thermal microwave radiation emissions emanating from the lower reaches of the atmosphere. Proplyds of planetars? Recently, it has been discovered that some extrasolar planets such as the planemo 2M1207b, orbiting the brown dwarf 2M1207, have debris discs. If interstellar planets are considered as stars (brown sub-dwarfs) then the debris could coalesce into planets, meaning the disks are proplyds. If these are considered planets, then the debris would coalesce as moons. The term planetar exists for those accretion masses that seem to fall between stars and planets. Interstellar planets in popular culture The short story A Pail of Air by Fritz Leiber, which first appeared on the radio show X Minus One in March 1956, is narrated by a boy living on Earth after it has been torn from the Sun's gravity and ejected into space by a passing "dark star". The Earth in this story has become an interstellar planet. The homeworld of the Founders in Star Trek: Deep Space Nine is a rogue planet in a nebula; it has climactic conditions capable of supporting humanoid life. In an episode of Star Trek: Enterprise, Enterprise happens upon a rogue planet with an earth-like atmosphere. The planet was heated by volcanic vents that sent heat into the atmosphere, thus sustaining the ecology of the planet In the Warhammer 40,000 universe, the Temple of the Culexus Assassins of the Officio Assassinorum is located deep under the surface of a 'dead' rogue planet. See also | ||||||||
|
| |||||||||
 |
|
| |